Device for recording and/or reproducing high-frequency signals, more particularly television signals



Apnl 2, 1963 F. T. BACKERS 3,084,225

DEVICE FOR RECORDING AND/OR REPRODUCING HIGH-FREQUENCY SIGNALS, MOREPARTICULARLY TELEVISION SIGNALS Filed March 30. 1959 FIG.1 Fl 6.2

INVENTOR FRANCISCU 5 TH EODORUS BICKERS United States Patent 3,084,225DEVICE FGR RECORDWG AND/R REPRODUC- ING HiGl-l-FREQUENQY SEGNALS, MGREPAR- TICULARLY TELEVHSHGN SEGNALS Franciscus Theodor-us Backers,Eindhoven, Netherlands, assignor to North American Philips Company,lino, New York, N.Y., a corporation of Delaware Filed Mar. 30, 1959,Ser. No. 802,745 Claims priority, application Netherlands Apr. 12, 19581 Claim. ((31. l79100.2)

This invention relates to devices for recording and/or reproducinghigh-frequency signals, more particularly television signals, by meansof a fixed current conductor, which has the high-frequency signalsderived from it or supplied to it by means of a quick-rotating wheelconstituted by pole-pieces and magnetic yokes traversed by the magneticflux. Such a device is known, for example, from British patentspecification No. 760,874. In this device, the magnetic flux coupled tothe current conductor is transmitted to the wheel or derived therefrom,through a fixed yoke and an air gap.

The device according to the invention is characterized in that thecurrent conductor is passed as a single stretched wire through anaperture provided at the centre of the wheel, the magnetic flux beingtransmitted between the current conductor and the wheel solely throughair. When comparing the above-mentioned known device with the deviceaccording to the invention, in which only air is used as a mediuminstead of fixed yokes, it appears that the arrangement of the currentconductor in the cavity is less critical than the positioning of thefixed yoke along the wheel.

In one practical embodiment of the device according to the invention,the wheel is arranged on one extremity of a hollow shaft, the otherextremity of which is provided with a driving roller (rope pulley) whichcauses the wheel to rotate, at for example, a speed of 48,000revolutions/ min. For writing about 16,000 lines of a television imageper second, of which, for example, in each case '10 lines are on oneline of the magnetic record carrier, two rotating gaps on the wheelwould be sufiicient. The magnetic carrier must then be bent by 180 roundthe wheel. When use is made of more than two rotating gaps, it ispossible to employ a carrier of smaller Width, which in this case isbent round the wheel by a correspondingly smaller angle. The carrier isbent round the wheel locally in a manner known in the art. In order tocause the wheel to rotate at the high speed mentioned above, it isnecessary to use a wheel having a small diameter. In view of this fact,the device according to the invention is suitable more particularly forsmall size magnetic recorders intended for domestic use.

In order that the invention may be readily carried into effect, severalembodiments will now be explained in detail, by way of example, withreference to the accompanying drawing, in which corresponding parts areprovided with the same reference numerals.

FIG. 1 shows a longitudinal section of the device according to theinvention.

FIG. 2 is an elevation view of the quick-rotating wheel round which amagnetic carrier is bent.

FIG. 3 is a perspective view of the manner in which the carrier, whichis initially fiat, is gradually bent as it approaches the wheel and,

FIG. 4 shows a device which may be used in combination with a flatcarrier.

Referring to FIG. 1, reference numeral 1 indicates the quick-rotatingwheel according to the invention, which is mounted on a hollow shaft 2.The shaft 2 which is journalled in a bearing block 3, also carries asmall rope pulley 4 for driving the shaft at a speed of, for example,48,000 revolutions per minute. The wheel 1 has a central aperture whichadjoins the cavity of the shaft 2. Passed through these cavities is acurrent conductor 5; the flux traversing the yokes arranged on the Wheelinduces a potential difference in the conductor when a televisionprogram is reproduced and the flux supplies a potential difference whena television program is recorded.

FIG. 2 is an elevation view of the quick-rotating wheel 1 in which threegaps 6 are formed between the polepieces of the various magnetic yokes.The current conductor 5 is arranged in the aperture of the wheel, andbent round the wheel is a magnetic carrier 7 which is moved in adirection at right angles to the plane of drawing.

FIG. 3 is a perspective view of the manner in which the flat carrier '7gradually bends round the device of FIG. 1. The Wheel 1 in this case hastwo gaps and the magnetic carrier must be bent round the wheel through3180. If more gaps are formed on the Wheel, the carrier must be bentthrough a correspondingly smaller angle. Thus, in the case of FIG. 2,where three gaps are shown, the carrier need be bent round the wheelthrough only FIG. 4 shows a variant of the device of FIG. 1, in whichthe carirer 7 is moved as a flat carrier along the gaps of the wheel 1.By means of a guide roller 8, the carrier is bent so that it can bemoved along the front surface of the wheel 1.

What is claimed is:

A magnetic head for recording or reproducing high frequency signalscomprising a quick-rotating wheel having a flat front surface andcontaining a plurality of magnetic pole pieces separated by a pluralityof gaps, means for rotating said wheel, said wheel having a hollowcentral aperture and an axis, a guide roller, a magnetic carrier movingaround said guide roller and adjacent to said gaps along said fiat frontsurface in flat position, and a stationary single current conductorpassing through said aperture at a substantially right angle to saidfiat front surface and along said axis, high frequency signals beingsupplied to the wheel from said conductor for signal recording, highfrequency signals being supplied to the conductor from said wheel duringsignal reproduction, said conductor being substantially parallel to theportion of said carrier at one side of said roller and substantiallyperpendicular to the portion of said carrier at the other side of saidroller.

References Cited in the file of this patent UNITED STATES PATENTS2,743,320 Daniels et a1 Apr. 24, 1956 2,835,743 Mufliey May 20, 19582,909,616 Marty Oct. 20, 1959 2,985,863 Buslik May 23, 1961 FOREIGNPATENTS 760,874 Great Britain Nov. 7, 1956 1,188,391 France Mar. 19',1959

